Is this the pattern?

Math makes my head spin...I'm going to sit back and read LOL

That is a beautiful quilt. I would love to make one using just blue and white fabric.

This is a 5x5 block - each section is undoubtedly 2" finished. If you make each section 2-1/2" finished you will end up with a 12-1/2" block. It's easier to cut the strips 3" and end up with a 12-1/2" finished block than to try to make a 12" block.

Whew! I'm glad that one is over. When I change the size of a pattern for a larger block, I just lay the 10 inch block piece on a piece of white paper and increase 1/2 inch around then redraw piece. Makes sense to me. A 10 inch block with 1/4 seam allowance + 10.5 add 2 inches to that and you get a pattern piece of 12.5 inches. Easier than all that figuring our.

Yes ksea that's the pattern. The other one is the double pinwheel in Quilt magazine Dec/Jan 2012 issue The quilt is called Sibling Rivalry and it uses the double pinwheel block, in the mag it is for a 10" block, I need a 12" finished size.
Thanks again everyone for all your help.

Do you want a bigger block so that you can get to a specific size quilt? If so, could you add another row of 10" blocks to the side and bottom? Or, if it's a design that would look lopsided if you did that (which I think Diamond Candy would), could you add a half-block along each side?

I use this alot :thumbup: :thumbup:

This is what I would do. Just remember to add 1/2" to every measurement in the cutting stage of your pattern.

thanks for the link